A Massachusetts man who the FBI says has traveled to Yemen and Pakistan for training in how to kill American soldiers now has a $50,000 price on his head.

Ahmad Abousamra, 31, last lived in the U.S. in a tony Boston suburb and has relatives in Detroit. He left the United States in 2006 and may now be living in Aleppo, Syria, with his wife, at least one daughter and other relatives. He was indicted in 2009 for taking multiple trips to Pakistan and Yemen to seek jihad training and has been charged with conspiracy to provide material support to Al Qaeda.

“Knowing that the public is the FBI’s best ally in finding fugitives, today we’re requesting your assistance to locate Abousamra,” said Richard DesLauriers, special agent in charge of the FBI’s Boston office.

One of Abousamra’s distinguishing characteristics is his higher-pitched voice, which can be heard on the FBI’s website. He also has dual U.S. and Syrian citizenship, is fluent in English and Arabic, and has a college degree in computer technology.

Abousamra’s co-conspirator, Taerk Mehanna, was convicted of terrorism charges by a federal jury in December 2011. He was sentenced last year to more than 17 years in prison.

“Both men were radicalized and used the Internet to educate themselves,” said Special Agent Heidi Williams, a member of the Joint Terrorism Task Force (JTTF) in Boston. “They came to it independently, but once they found each other, they encouraged each other’s beliefs.”

Both Abousamra and Mehanna were inspired by the Sept. 11, 2001, terror attacks, she said.

“They celebrated it,” Williams said.

Lowell Police Department Sgt. Thomas Daly, a member of Boston’s JTTF since 2002, said apprehending Abousamra will “close the chapter” on another alleged terrorist intent on killing American troops abroad.

Abousamra, who has dark brown hair and brown eyes, stands 5 feet, 11 inches tall and weighed roughly 170 pounds at the time of his disappearance. Anyone with information regarding his whereabouts is asked to contact FBI officials at (800) CALL-FBI.

“These two were actively radicalizing others,” Daly said. “We can only assume Abousamra is still on the same path and remains a threat to our soldiers overseas.”